Internal down tube gear wire sticks

I have a bike that uses a STI gear wire is enclosed in the downtube with a liner that hangs out the BB guide and then goes naked to the start of the derailleur cable-housing. It was replaced a year ago, but after not riding over the winter it is already sticky again.

I can't get to the outermost cog, and it begins to up shift slowly on the last two or three cogs.

If i replace the wire again - is there anything else I can do to assure better shifting? I already tried to "lube it" - so I probably may have screwed it up anyway...... I dripped light weight lube in to the liner while bike was upside down.

I like Slick 50 a lot. I periodically hose my shifters with this stuff. Still, shifting should not be totally dependent on lube. I would suspect a bad bend somewhere in the cable. The housings are usually lined with a nylon sleeve and this is almost as friction free as you can get. I'd be looking for something beyond the obvious.